method e compile_step2
  arg_rw Expression e

Attempts to compile the expression just as method compile would do, but do not set error message if compiling fails.

function e compile_step3
  arg_rw Expression e

If the expression fails to compile, method  compile_step2  or compile  would attempt to rearrange it a bit, then retry before surrendering whereas compile_step3 will not.

function e compile_step4 value access
  arg_rw Expression e ; arg address value ; arg Int access

Same as compile_step3 method, but consider that the parsing content of the expression is stored at 'address' and has 'access' access rights rather than assuming that it's address is in the  value field and that it is a constant.